Our working hypothesis in this Program is that chemical species generated by phagocytes at sites of inflammation represent a causative link to human disease. Project 1 focuses on reactions of the chemical mediators of inflammation with DNA, lipids, and proteins in epithelial cells, which lead to altered physiology, cell death and mutations associated with cancer. The objectives are to explore the mechanisms of this damage, to develop surrogate markers of the labile inflammatory mediators, and to develop candidate biomarkers of inflammation. The methods and results from Project 1 will be translated to Projects 2, 3, and 4 to test hypotheses about the link between chemical changes and biological effects in cell and animal models. In the last funding period, we developed methods to quantify DNA, RNA and protein damage products that represent key markers of inflammation chemistry resulting from neutrophil and macrophage activity, including the protein lesions 3-chloro- and 3-nitro-tyrosine, and DNA and RNA damage caused by oxidation (8-oxo-guanine, spiroiminodihydantoin, guanidinohydantoin, oxazolone), deamination (xanthine, hypoxanthine), halogenation (5-chlorocytidine) and electrophile reactions (etheno adducts of A, G and C). These analytical methods are now mature enough to be moved into Core A as routine assays. We now propose to expand the development and application of biomarker candidates to test a variety of hypotheses that have arisen from results obtained in the last funding period.